Using the unique infrared sensitivity of NASA's James Webb Space Telescope, astronomers have made a groundbreaking discovery that could change our understanding of the early universe. A team of international researchers has identified bright hydrogen emission from a galaxy that existed a mere 330 million years after the Big Bang, a time when the universe was still in its infancy. This unexpected finding is challenging existing theories on how light could have pierced through the dense fog of neutral hydrogen that filled space during that period.
The galaxy, known as JADES-GS-z13-1, was discovered by Webb’s Near-Infrared Camera (NIRCam) as part of the James Webb Space Telescope Advanced Deep Extragalactic Survey (JADES). The galaxy's remarkable distance from Earth, estimated through the redshift measurement, puts its light at a stage of cosmic history that is far earlier than previously thought possible. The initial redshift estimate from NIRCam was 12.9, indicating that the galaxy formed just 330 million years after the Big Bang, a tiny fraction of the universe’s present age of 13.8 billion years.
To verify this extreme redshift, an international team led by Joris Witstok from the University of Cambridge, with contributions from the Cosmic Dawn Center and the University of Copenhagen, employed Webb's Near-Infrared Spectrograph (NIRSpec) to analyze the galaxy’s light. Their results confirmed the redshift of 13.0, solidifying the galaxy’s ancient origins.
However, one unexpected feature stood out in the galaxy's spectrum: a strong, clear emission of Lyman-alpha light, radiated by hydrogen atoms. This emission is particularly important as it indicates the presence of energetic ultraviolet light, which was thought to be blocked by the dense fog of neutral hydrogen that enveloped the universe during its early stages.
“The early universe was bathed in a thick fog of neutral hydrogen,” said Roberto Maiolino, a researcher from the University of Cambridge and University College London. “Most of this haze was lifted in a process called reionization, which was completed about one billion years after the Big Bang. GS-z13-1 is seen when the universe was only 330 million years old, yet it shows a surprisingly clear, telltale signature of Lyman-alpha emission. This finding contradicts existing theories about early galaxy formation and has taken astronomers by surprise.”
During the reionization era, the universe was shrouded in a fog of neutral hydrogen, blocking much of the light emitted by early galaxies. This haze prevented the escape of ultraviolet light, including Lyman-alpha emission, until enough stars had formed and ionized the surrounding hydrogen gas. The discovery of Lyman-alpha radiation from JADES-GS-z13-1 suggests that this galaxy might have played a role in lifting this cosmic fog far earlier than previously understood.
“We shouldn’t have found a galaxy like this based on our current models of the universe’s evolution,” said Kevin Hainline, a researcher at the University of Arizona. “The early universe was like a thick fog that would have made it difficult for even the most powerful galaxies to emit light. Yet, here we are, seeing this galaxy’s light piercing through the veil. This unexpected emission has significant implications for the timing and process of reionization.”
While the source of this Lyman-alpha radiation is still uncertain, the researchers suggest that it could be the result of the first stars to form in the universe, which were likely far more massive and luminous than stars formed in later epochs. Another possibility is that an active galactic nucleus, powered by one of the first supermassive black holes, might be responsible for the emission.
This discovery marks a significant milestone in our quest to understand the early universe and was published in Nature on Wednesday.
The James Webb Space Telescope, a collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA), continues to be the world’s leading space observatory. It is unlocking mysteries not only within our solar system but also in distant galaxies, providing unprecedented insights into the origins of our universe and our place within it.
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